The present invention relates, in general, to golf club heads, and in particular, to a golf club iron that can be part of a golf club set in which each iron has an inner soft core and a hard outer coating.
Prior art golf club heads are typically composed of a number of layers. A core of forged mild carbon steel is used in conjunction with a decorative nickel coating followed by a decorative layer of bright chrome. Depending on the bonding capabilities of the nickel layer, a copper strike layer or plating is first applied to the carbon steel core to improve adhesion of the nickel layer.
The decorative chrome used on prior art golf clubs has a hardness of about 35 to 45 on the Rockwell C scale. The typical thickness of the decorative chrome layer is usually between 0.00005 inches to 0.0002 inches. Thus, a prior art golf club head, as shown in FIG. 1, consists of an inner core 9 of forged mild carbon steel and an outer coating 7 of decorative nickel and decorative chrome. Forging produces a club with acceptable feel characteristics to a golfer at a reasonable cost.
Forging, in general terms, is the process by which metal is shaped by hammering or cogging. While most malleable metals may be shaped in the cold state, the application of heat permits a greater deformation with any given expenditure of energy. Great care must be taken with any forging process due to the high oxidation rate of the metal when it is heated for too long a time period. This over-exposure to elevated temperatures inherently weakens the metal. It also results in a less than desirable surface, characterized by a lack of smoothness. Although forging has been used to construct golf clubs, this method of constructing golf clubs has several faults.
The process itself lacks consistency due to inherent characteristics of the forging process. The clubs lack durability due to the softer and weaker decorative nickel and decorative chrome. Furthermore, because forged mild carbon steel has a tendency to rust, any damage to the integrity of the decorative nickel or decorative chrome coating will inevitably lead to the inside of the club being weakened as well. During the finishing process, inconsistencies can occur due to many manual operations, such as grinding, shaping, milling and polishing. Heads can become warped during the stamping operation due to excessive pressure and incorrect fitting of nest dies.
There is, therefore, a need in the art for golf club irons which possess the acceptable feel characteristics of forged mild carbon steel clubs, but which are more durable and which possess characteristics which are consistent from club to club or iron to iron.
An object of the present invention is to provide an improved golf club iron, specifically a golf club iron with a head that has greater consistency from club to club than is the case with conventional forged steel golf club irons.
Another object of the present invention is to provide a golf club iron with an outstanding soft feel, but without a tendency to rust, as would be caused by forging iron clubs from conventional mild carbon steel.
Yet another object of the present invention is to provide a golf club iron that is more durable than prior art club irons.
These and other objects of the present invention will become apparent from a review of the description provided below.
The present invention is an iron or a set of golf club irons and the method of manufacturing such golf club irons. The golf club iron heads comprise a multilayer construction having a soft nickel alloy core and a hard chrome coating. The process of the present invention involves an investment casting process in which the soft nickel alloy core is cast and the hard chrome coating is plated to the core. This multilayer design produces a golf club iron that is durable and consistent from club to club or iron to iron with feel characteristics which are generally equal to or better than traditional clubs formed from forged mild carbon steel.
The above and other features of the invention, including various novel details of construction and combination of materials, will now be more particularly described with reference to the accompanying drawing.